templatekw: rename variable current to active

Today, the terms 'active' and 'current' are interchangeably used throughout the
codebase in reference to the active bookmark (the bookmark that will be updated
with the next commit). This leads to confusion among developers and users.
This patch is part of a series to standardize the usage to 'active' throughout
the mercurial codebase and user interface.

mercurial/templatekw.py

@@ -227,9 +227,9 b' def showcurrentbookmark(**args):'
     import bookmarks as bookmarks # to avoid circular import issues
     repo = args['repo']
     if bookmarks.isactivewdirparent(repo):
-        current = repo._activebookmark
-        if current in args['ctx'].bookmarks():
-            return current
+        active = repo._activebookmark
+        if active in args['ctx'].bookmarks():
+            return active
     return ''
 
 def showdate(repo, ctx, templ, **args):